基于全流道非定常流动计算的轴流式水轮机尾水管压力脉动分析

Analysis of pressure fluctuation in draft tube based on simulation of unsteady flow in whole passage of axial flow turbine

以轴流式水轮机全流道三维非定常湍流数值模拟为基础,对轴流式水轮机尾水管内的非定常流场进行了分析,研究了尾水管内涡带的形态,对尾水管压力脉动的幅值和频率特点进行了分析。结果表明,大流量工况时,在尾水管内形成了一个与转轮旋转方向相反低压涡带,引发了低频压力脉动,这种低频压力脉动是水轮机中压力脉动的主要脉动源之一。

Based on 3-D unsteady turbulent flow numerical simulation of the whole passage in axial flow turbine, the unsteady flow field in draft tube is analyzed in this paper. The shape of vortex rope in draft tube is studied. The pressure fluctuation in draft tube is analyzed by the characteristics of amplitude and frequency. The result shows that a vortex rope with low pressure comes into draft tube under large discharge condition. The rotation direction of the vortex rope is opposite to the rotation direction of the runner. The vortex rope caused by pressure fluctuation with tow frequency is one of the main vibration sources in hydraulic turbine.